Changes in equine hindgut bacterial populations during oligofructose-induced laminitis.

This research looks into the changes that occur in the bacterial populations of a horse’s hindgut when it develops laminitis due to an overload of carbohydrates, focusing specifically on oligofructose-utilizing organisms. The study used microbial ecology methods to monitor this change and found that the bacterium Streptococcus infantarius ssp. coli was the most dominant oligofructose-utilizing organism present before lameness set in.

Objective and Method

• This study was conducted to understand the changes in the bacterial populations within the horse’s hindgut during laminitis, a condition often triggered by an overload of carbohydrates.
• An attempt was made to identify the dominant bacteria which utilize oligofructose, a carbohydrate believed to play a crucial role in triggering this condition.
• For this study, laminitis was experimentally induced in five horses through the administration of oligofructose, and faecal specimens were collected at regular eight-hour intervals.
• A habitat-simulating medium was then used to culture and enumerate the hindgut microbiota capable of utilizing oligofructose.
• The isolated bacteria were identified through 16S rRNA gene sequencing.

Main Findings

• The majority of the cultured isolates belonged to the genus Streptococcus, with 91% being most closely related to Streptococcus infantarius ssp. coli.
• This species was the most dominant oligofructose-utilizing organism isolated before the onset of lameness, which is a symptom of laminitis.
• Fluorescence in situ hybridization (FISH) probes were developed to target the isolated Streptococcus spp. which revealed a significant population increase between 8 and 16 hours post oligofructose administration.
• However, this was followed by a sharp decline in the population which coincided with a fall in faecal pH and lameness setting in.

Conclusion

• The investigation suggests a role of Streptococcus bovis/equinus complex in the development of laminitis in horses. This emphasizes the need for further research into the involvement and management of hindgut microbial populations in equine health.